Refrigerator unit and/or freezer unit

ABSTRACT

The present invention relates to a refrigerator unit and/or a freezer unit having a magnetic refrigerator, having a cold heat exchanger for the refrigeration of the refrigerator space and/or freezer space of the unit as well as having control means, wherein the control means are made such that, in the refrigerating mode of the unit, the heat carrier medium refrigerated in the magnetic refrigerator is supplied to the cold heat exchanger, wherein the control means are furthermore made such that the magnetic refrigerator is switched off in the defrosting mode of the unit; or in that the heat carrier medium heated in the magnetic refrigerator is supplied to the cold heat exchanger.

The invention relates to a refrigerator unit and/or a freezer unit having a magnetic refrigerator, having a cold heat exchanger for the refrigerating of the refrigeration space and/or freezing space, and having control means, with the control means being made such that the heat carrier medium refrigerated in the magnetic refrigerator in the refrigerating mode of the unit is supplied to the cold heat exchanger.

In magnetic refrigerating, a heat carrier medium is heated and cooled offset in time while utilizing the so-called magnetocaloric effect, with usually four process steps, namely the magnetization, the heat removal, the demagnetization and the cold utilization, being repeated continuously. It is, for example, known to use a stationary magnetocaloric material and rotating magnets, with the magnetocaloric material undergoing heating based on magnetization or cooling based on demagnetization in dependence on the position of the rotating magnet, said heating or cooling ultimately being used for the heating or cooling of a heat carrier medium.

A conceivable refrigeration circuit includes a cold heat exchanger, the magnetic refrigerator, a hot heat exchanger and a pump for the conveying of the heat carrier medium. The heat carrier medium flowing through the magnetic refrigerator is heated during the magnetization and is then guided by means of the named pump into the hot heat exchanger in which it is cooled. During the demagnetization, the heat carrier medium flowing through the magnetic refrigerator is then cooled further and subsequently flows through the cold heat exchanger which is usually located in the refrigeration space or in the freezer space or in the region thereof and which serves the taking up of heat from this space. The heat carrier medium heated in this manner in the cold heat exchanger is then further heated during the magnetization in the magnetic refrigerator and subsequently again moves via the pump to the hot heat exchanger.

It can occur during operation that the cold heat exchanger ices up so that it has to be defrosted. The defrosting usually takes place for so long until a specific temperature value has been reached; subsequently, the refrigerating circuit is again put into operation as described above and a refrigerating of the refrigeration space or freezer space takes place by means of the cold heat exchanger through which cold heat medium flows.

It is the object of the present invention to further develop a refrigerator unit and/or a freezer unit of the initially named kind such that the defrosting time is reduced.

This object is solved by a refrigerator unit and/or a freezer unit having the features of claim 1. Provision is accordingly made that the control means are furthermore made such that in the defrosting mode of the unit the heat carrier medium heated in the magnetic refrigerator is supplied to the cold heat exchanger. In contrast to the refrigerating operation in which the heat carrier medium cooled in the magnetic refrigerator is supplied to the cold heat exchanger, provision is now made in the defrosting mode that the heat carrier medium heated in the magnetic refrigerator is supplied to the cold heat exchanger, whereby its temperature increases faster and the defrosting time is accordingly reduced. It is also conceivable to switch off the magnetic refrigerator in the defrosting mode of the unit while the pump conveying the heat carrier medium continues to run. A change to any valve circuit present is not necessary in this process.

The control means preferably include valves arranged downstream of the cold heat exchanger and upstream of the magnetic refrigerator in the direction of flow as well as a valve control by means of which the valves can be controlled. The valves can, for example, be bistable valves or monostable valves.

In this embodiment. of the invention, the valves are used such that they conduct the heat carrier medium in the refrigerating mode such that heat carrier medium cooled in the magnetic refrigerator is supplied to the cold heat exchanger and heat carrier medium heated in the magnetic refrigerator is supplied to the hot heat exchanger. In accordance with the invention, the control means are made such that now a circuit reversal takes place in the defrosting mode, said circuit reversal consisting of the fact that during the defrosting the valves supply the heat carrier medium heated in the magnetic refrigerator to the cold heat exchanger and the heat carrier medium refrigerated in the magnetic refrigerator to the hot heat exchanger

Accordingly, in a further embodiment, a hot heat exchanger can be provided, with one of the valves being able to be arranged between the hot heat exchanger and the magnetic refrigerator.

The magnetic refrigerator can include two or more than two heat exchanger units which are made such that a heating and cooling of the heat carrier medium flowing through them takes place periodically in them.

It is conceivable that the heat exchanger units of the magnetic refrigerator consist of a material or comprise a material which warms on magnetization and cools on demagnetization and that the magnetic refrigerator furthermore has a magnet moved, preferably rotating, relative to the heat exchanger units. Depending on the position of the rotating magnet, a heating of the magnetocaloric material takes place in one of the heat exchanger units. This has the result that the heat carrier medium flowing through this heat exchanger unit is heated. The other heat exchanger unit, in which the rotating magnet is not located, that is, which is demagnetized, undergoes a cooling due to the magnetocaloric effect, said cooling having the consequence that the heat carrier medium which flows through this heat exchanger unit is cooled.

Alternatively to such an embodiment with a rotating magnetic, it is generally equally conceivable that the magnetocaloric material rotates and the magnet is stationary or also that the magnetocaloric material is taken up in the heat carrier medium, for example in the form of a suspension.

Provision is finally made in a further embodiment of the invention that the control means are made such that the changeover from the refrigerating mode to the defrosting mode takes place by a time offset in the control of the valves or in the operation of the magnetic refrigerator. It is thus conceivable when changing over from the refrigerating mode to the defrosting mode or also when changing over from the defrosting mode to the refrigerating mode, to continue to operate the magnetic refrigerator in unchanged form and only to change the flow conducting of the heat carrier medium by a time offset of the valve control. This time offset is changed such that the valve located upstream of the magnetic refrigerator supplies the heat carrier medium to the heat exchanger unit in which a heating of the heat carrier medium takes place and then supplies it to the cold heat exchanger. Provision can furthermore be made that the valve arranged downstream of the cold heat exchanger supplies the heat carrier medium heated slightly in the cold heat exchanger to the heat exchanger unit of the magnetic refrigerator in which a cooling of the heat carrier medium takes place.

It is equally conceivable to continue to operate the valves in an unchanged manner and to effect a time offset in the operation of the magnetic refrigerator.

As soon as the defrosting has ended, a repeated time offset of the valves or of the magnetic refrigerator takes place in that the heat carrier medium is first supplied to the cold heat exchanger unit of the magnetic refrigerator and flows from there into the cold heat exchanger and that the heat carrier medium exiting the cold heat exchanger is supplied to the hot heat exchanger unit of the magnetic refrigerator and flows from there into the hot heat exchanger again.

It is also possible to achieve the defrosting by a reversal of the conveying direction of the heat carrier medium. The magnetic refrigerator can continue to run in this process. The same applies correspondingly to the switching of the valves.

The term the “reversal of the conveying direction” is to be understood such that the heat carrier medium flows through the system in a reverse direction to the refrigerating mode. This can be achieved by a reversal of the conveying direction of the pump or in that the conveying direction of the pump remains unchanged and the conveying direction of the heat carrier medium is effected by a changed line connection.

Further details of the invention will be explained with reference to an embodiment shown in the drawing.

Reference numeral 10 marks the magnetic refrigerator which includes two heat exchanger units 12, 14 which can be made as a construction unit or also separately from one another. These heat exchanger units consist of a magnetocaloric material or comprise such a material. The cyclic magnetization and demagnetization is carried out by a rotating magnet, not shown, which rotates around the heat exchanger units 12, 14. Depending on the position of the rotating magnet, the heat exchanger units 12, 14 are magnetized or demagnetized, which has the consequence of their heating or cooling. Accordingly, the heat carrier medium guided through the heated heat exchanger unit undergoes a heating and the heat carrier medium guided through the cooled heat exchanger unit undergoes a cooling.

As can furthermore be seen from the FIGURE, the refrigerator unit and/or freezer unit furthermore includes a cold heat exchanger 20 which is arranged in the refrigeration space or the freezer space or in the region of the refrigeration space or the freezer space and provides the cooling thereof. A hot heat exchanger is arranged on the outer side of the unit and serves the heat removal from the heat carrier medium to the environment or to another heat carrier medium.

The pump 100 provides the flow of the heat carrier medium through the refrigerating circuit shown.

As can furthermore be seen from the FIGURE, a valve 40 is arranged downstream of the cold heat exchanger 20 and a further valve 30 is arranged downstream of the hot heat exchanger 50. The valves are, for example, bistable valves or monostable valves.

During the refrigerating process, the valve 40 is controlled by means of a valve control, not shown, so that the heat carrier, for example brine or an alcohol mixture, flows through the heat exchanger unit 12/14 which is in the magnetized state and is therefore heated and thus emits heat to the heat carrier medium. The heat carrier heated in this manner is then conducted to the hot heat exchanger 50 outside of the refrigerating device by means of the pump 100. The valve 30 is controlled such that the heat carrier medium cooled in the hot heat exchanger 50 is guided through the heat exchanger unit 12/14 of the magnetic refrigerator, said heat exchanger unit being in the demagnetized state and therefore refrigerated. In this manner, the heat carrier medium is refrigerated in the heat exchanger unit 12/14 and then moves into the cold heat exchanger 20.

For the purpose of defrosting, the valve control is changed, within an unchanged operation of the magnetic refrigerator 10, such that a time offset, i.e. a phase shift, takes place with respect to the operation of the magnetic refrigerator 10. The valve 40 is controlled in such a time offset manner that heat carrier medium is guided through the cold, i.e. demagnetized, heat exchanger unit 12/14 of the magnetic refrigerator after flowing through the cold heat exchanger 20 and the valve 30 is controlled such that the heat carrier medium exiting the hot heat exchanger 50 is guided through the hot, that is, magnetized, heat exchanger unit of the magnetic refrigerator 10. In this manner, a circuit reversal is achieved to the effect that the heat carrier medium flows through the cold heat exchanger which has undergone a heating in the magnetic refrigerator 10, which has the consequence that the defrosting time of the cold heat exchanger can be reduced accordingly.

The advantage thereby results that the temperatures in the refrigerating device are more stable or fluctuate less. 

1. A refrigerator unit and/or a freezer unit having a magnetic refrigerator (10), having a cold heat exchanger (20) for the refrigeration of the refrigerator space and/or freezer space of the unit as well as control means, wherein the control means are made such that, in the refrigerating mode of the unit, the heat carrier medium refrigerated in the magnetic refrigerator (10) is supplied to the cold heat exchanger (20), and the control means are furthermore made such that the magnetic refrigerator (10) is switched off in the defrosting mode of the unit; or in that the heat carrier medium heated in the magnetic refrigerator (10) is supplied to the cold heat exchanger (20).
 2. A refrigerator unit and/or a freezer unit in accordance with claim 1, wherein the control means include valves (30, 40) arranged downstream of the cold heat exchanger (20) and upstream of the magnetic refrigerator (10) in the flow direction of the heat carrier medium as well as a valve control.
 3. A refrigerator unit and/or a freezer unit in accordance with claim 2, wherein the unit furthermore has a hot heat exchanger (50); and one of the valves (30) is arranged between the hot heat exchanger (50) and the magnetic refrigerator (10).
 4. A refrigerator unit and/or a freezer unit in accordance with claim 1, wherein the magnetic refrigerator (10) includes two or more than two heat exchanger units (12, 14) which are made such that a heating and cooling of the heat carrier medium flowing through them takes place cyclically in them.
 5. A refrigerator unit and/or a freezer unit in accordance with claim 1, wherein the heat exchanger units (12, 14) is composed of a magnetocaloric material or contain such a material; and the magnetic refrigerator (10) furthermore has a magnet moved relative to the heat exchanger units (12, 14).
 6. A refrigerator unit and/or a freezer unit in accordance with claim 1, wherein the control means are made such that the changeover from the refrigerating mode to the defrosting mode takes place by a time offset in the control of the valves (30, 40) or time offset of the operation of the magnetic refrigerator (10) or reversal of the conveying direction of the heat carrier medium.
 7. A refrigerator unit and/or a freezer unit in accordance with claim 5, wherein said magnet is rotatable relative to the heat exchanger units (12, 14).
 8. A refrigerator unit and/or a freezer unit in accordance with claim 2, wherein the magnetic refrigerator (10) includes two or more than two heat exchanger units (12, 14) which are made such that a heating and cooling of the heat carrier medium flowing through them takes place cyclically in them.
 9. A refrigerator unit and/or a freezer unit in accordance with claim 3, wherein the magnetic refrigerator (10) includes two or more than two heat exchanger units (12, 14) which are made such that a heating and cooling of the heat carrier medium flowing through them takes place cyclically in them.
 10. A refrigerator unit and/or a freezer unit in accordance with claim 2, wherein the heat exchanger units (12, 14) is composed of a magnetocaloric material or contain such a material; and the magnetic refrigerator (10) furthermore has a magnet moved relative to the heat exchanger units (12, 14).
 11. A refrigerator unit and/or a freezer unit in accordance with claim 3, wherein the heat exchanger units (12, 14) is composed of a magnetocaloric material or contain such a material; and the magnetic refrigerator (10) furthermore has a magnet moved relative to the heat exchanger units (12, 14).
 12. A refrigerator unit and/or a freezer unit in accordance with claim 4, wherein the heat exchanger units (12, 14) is composed of a magnetocaloric material or contain such a material; and the magnetic refrigerator (10) furthermore has a magnet moved relative to the heat exchanger units (12, 14).
 13. A refrigerator unit and/or a freezer unit in accordance with claim 8, wherein the heat exchanger units (12, 14) is composed of a magnetocaloric material or contain such a material; and the magnetic refrigerator (10) furthermore has a magnet moved relative to the heat exchanger units (12, 14).
 14. A refrigerator unit and/or a freezer unit in accordance with claim 9, wherein the heat exchanger units (12, 14) is composed of a magnetocaloric material or contain such a material; and the magnetic refrigerator (10) furthermore has a magnet moved relative to the heat exchanger units (12, 14).
 15. A refrigerator unit and/or a freezer unit in accordance with claim 2, wherein the control means are made such that the changeover from the refrigerating mode to the defrosting mode takes place by a time offset in the control of the valves (30, 40) or time offset of the operation of the magnetic refrigerator (10) or reversal of the conveying direction of the heat carrier medium.
 16. A refrigerator unit and/or a freezer unit in accordance with claim 3, wherein the control means are made such that the changeover from the refrigerating mode to the defrosting mode takes place by a time offset in the control of the valves (30, 40) or time offset of the operation of the magnetic refrigerator (10) or reversal of the conveying direction of the heat carrier medium.
 17. A refrigerator unit and/or a freezer unit in accordance with claim 4, wherein the control means are made such that the changeover from the refrigerating mode to the defrosting mode takes place by a time offset in the control of the valves (30, 40) or time offset of the operation of the magnetic refrigerator (10) or reversal of the conveying direction of the heat carrier medium.
 18. A refrigerator unit and/or a freezer unit in accordance with claim 5, wherein the control means are made such that the changeover from the refrigerating mode to the defrosting mode takes place by a time offset in the control of the valves (30, 40) or time offset of the operation of the magnetic refrigerator (10) or reversal of the conveying direction of the heat carrier medium.
 19. A refrigerator unit and/or a freezer unit in accordance with claim 8, wherein the control means are made such that the changeover from the refrigerating mode to the defrosting mode takes place by a time offset in the control of the valves (30, 40) or time offset of the operation of the magnetic refrigerator (10) or reversal of the conveying direction of the heat carrier medium.
 20. A refrigerator unit and/or a freezer unit in accordance with claim 9, wherein the control means are made such that the changeover from the refrigerating mode to the defrosting mode takes place by a time offset in the control of the valves (30, 40) or time offset of the operation of the magnetic refrigerator (10) or reversal of the conveying direction of the heat carrier medium. 